1. Field of the Invention
The present invention relates to display devices, and in particular, to a method for arranging column and row drive lines in a display screen and a method for driving the lines.
2. Description of the Related Art
FIGS. 15A and 15B show the structure of a liquid crystal panel (display device) of the related art. Driving circuits for the liquid crystal panel are typically large in physical size and may require modifications so as to avoid extending the overall physical size of the liquid crystal panel. Thus, to realize a high-definition and small liquid crystal panel, as shown in FIGS. 15A and 15B, the driving circuits for the data lines are divided into upper driving circuits 101d and lower driving circuits 101e, disposed on two opposite sides, namely, the upper and lower sides of the display screen 101a. 
FIG. 16 is an enlarged illustration of portion B of the display screen 101a shown in FIG. 15A. A first group of alternate ones of the data lines Y1 to Y480 in the display screen 101a are routed to the upper side of the display screen 101a. The remainder (i.e., the second group of alternate ones of the data lines Y1 to Y480) are routed to the lower side of the display screen 101a. Hence, data lines leading to the upper side are connected to the upper driving circuits 101d, and data lines leading to the lower side are connected to the lower driving circuits 101e. Both driving circuits 101d and 101e are disposed on a single wiring plate P101 and are connected to the display screen 101a by the wiring plate P101.
By disposing the data lines Y1 to Y480 to lead as shown in the configuration in FIG. 16, dot inversion can be realized. The polarities of drive voltages applied to liquid crystal displays are typically reversed many times per second to prevent any deterioration of image quality resulting from dc stress. Dot inversion, which is also known as spatial dot inversion, refers to the technique whereby the polarities of driving voltages applied to adjacent dots in the display screen 101a are inverted. By using this technique, spatial frequency can be increased and picture quality having minimized flickering can be obtained. The dot inversion can be realized, for example, by using a driving voltage output from the upper driving circuit 101d as a positive polarity, using a driving voltage output from the lower driving circuit 101e as a negative polarity, and performing polarity inversion for each line or each field. This operation is made possible by adding a line-inverting driving circuit to a one-sided driving circuit.
FIG. 17 is a block diagram showing the detailed structure of a display device of the related art. This display device includes a display screen 101a, an upper driving circuit 101d, a lower driving circuit 101e, and a scramble circuit 101g. The upper driving circuit 101d includes a digital-to-analog (D/A) conversion circuit SHU12 for providing analog output signals to pixels Ga1 and Ga2 of the display screen 101a, a D/A conversion circuit SHU34 for providing analog output signals to pixels Ga3 and Ga4 of the display screen 101a, a D/A conversion circuit SHU56 for providing analog output signals to pixels Ga5 and Ga6, etc. The lower driving circuit 101e includes a D/A conversion circuit SHD12 for providing analog output signals to pixels Ga1 and Ga2 of the display screen 101a, a D/A conversion circuit SHD34 for providing analog output signals to pixels Ga3 and Ga4 of the display screen 101a, a D/A conversion circuit SHD56 for providing analog output signals to pixels Ga5 and Ga6, etc. The display screen 101a in FIG. 17 illustrates the pixels Ga1, Ga2, Ga3, etc., for only one line, and only data lines connected to dots constituting these pixels. Other data lines and pixel lines are omitted from the illustration for clarity purposes.
In order that the display screen 101a of the liquid crystal panel may show images in their natural colors, a scramble circuit 101g is required. Such a circuit changes the order of display data to be sent to the upper driving circuit 101d and the lower driving circuit 101e to correspond to the arrangement of color filters in the display screen 101a. Separate sets of bus lines are required to send display data from the scramble circuit 101g to the upper driving circuit 101d, and from the scramble circuit 101g to the lower driving circuit 101e. 
FIG. 18 is a timing chart for the display device of the related art. The chart shows the relationships among input data RD, GD, and BD for the scramble circuit 101g, display data UA, UB, and UC which are received by the upper driving circuit 101d after being transmitted from the scramble circuit 101g, and display data DA, DB, and DC which are received by the lower driving circuit 101e after being transmitted from the scramble circuit 101g. The scramble circuit 101g rearranges the order of the input data RD, GD, and BD to an order corresponding to the arrangement of color filters in the display screen 101a. 
To display an image properly on a display screen of a liquid display panel, i.e., so that the image natural colors are shown properly, the order of display data to be sent to driving circuits on two opposite sides of the display screen must be rearranged to the order corresponding to the arrangement of color filters in the display screen. To accomplish this, separate sets of display-data-bus lines must be formed on each of the two sides (e.g., an upper side and a lower side). This requires wiring areas for the bus lines on both sides, thus hindering size reduction of the display device.
In addition, since a scramble circuit generally includes logic circuits, logic circuits for the bus lines are required on both sides of the display screen. Furthermore, integrated circuits including scramble circuits of the above type require output pins for the bus lines on both sides of the display screen. This not only hinders reduction in the size of the display device, but also increases the display device cost.
Also, during inspection of the liquid crystal panel to diagnose problems found in a displayed picture, a portion causing the problem must be specified. Thus, in order to pinpoint the problem to one of the two sets of data lines leading to both sides of the display screen, driving of one set of data lines may be stopped.
In a structure in which data lines leading from a scramble circuit are connected in an alternating fashion to one of two sides of a display screen, as in the related art, when driving of data lines on one side is stopped, the data output from the driving circuits differs, depending on the which of the two driving circuits is involved. For example, if driving of data lines to an upper side driving circuit is stopped, black display data are output instead of, for example, a normally white liquid crystal panel. When a driving circuit on the lower side of the display screen is stopped, a stripe state occurs in which G, R, B, G, R, B, . . . are displayed on every other line. Accordingly, it is difficult to determine which side has a problem. Even if the side having the problem is determined, it is difficult to further localize the problem. For example, it is difficult to determine which data line from the side has a problem.
The present invention is made in view of the above-described problems, and it is an object of the present invention to provide a small, inexpensive display device which doesn""t require a scramble circuit for scrambling display data to be sent to driving circuits on two sides of the display screen of the display device, and which displays natural color pictures.
It is another object of the present invention to provide a small, inexpensive display device that includes a reduced number of display-data-bus lines for sending display data to driving circuits.
It is another object of the present invention to provide a display device in which, when a displayed picture has a problem, a portion causing the problem can easily be identified.
The present invention provides a display device including a pair of substrates, with electrooptical material provided therebetween, and a plurality of data lines and a plurality of scanning lines on a first substrate of the pair of substrates. The plurality of data lines and the plurality of scanning lines cross in the form of a matrix. The plurality of data lines include two mutually exclusive groups of data lines, a first group leading to a first side of the first substrate, and a second group of data lines leading to a second side of the first substrate, the first and second sides positioned so as to oppose each other. The display device includes a display screen in which the surface of the first substrate is divided into a plurality of dots by the plurality of data lines and the plurality of scanning lines. Each set of a predetermined number of adjacent dots constitutes one pixel. All data lines from the adjacent dots constituting one pixel lead to a single side of the first substrate, the particular side determined by the pixel location.
According to the above structure, data lines connected to dots constituting one pixel can be connected to a single driving circuit because they lead to a single side of a display screen. Therefore, the data lines can be driven by the single driving circuit. This arrangement eliminates the need for a scramble circuit to sort the order of display data to be input to driving circuits on two sides of the display screen. Hence, a small, inexpensive display device that can display natural color pictures can be provided.
Moreover, since a single driving circuit is provided, it is not necessary to provide separate sets of display-data-bus lines for connecting to driving circuits located on opposite sides of the display screen. Thus, the width of each bus line can be reduced, and a small, inexpensive display device can be provided.
Also, in testing of a displayed picture with a problem, the location of data lines on one side allows white color to be displayed by normal pixels. Hence, the display device can identify the location of the problem by reference to the non-white pixels.
Preferably, a plurality of pixels arranged along the scanning lines on the first substrate of the display screen are classified for each set of an odd number of pixels into a first group and a second group in the arranged order, the first group of data lines are connected to dots constituting the first group of pixels, and the second group of data lines are connected to dots constituting the second group of pixels.
Preferably, a plurality of pixels arranged along the scanning lines on the first substrate included in the display screen are classified for each set of an even number of pixels into a first group and a second group in the arranged order, the first group of data lines are connected to dots constituting the first group of pixels, and the second group of data lines are connected to dots constituting the second group of pixels.
The display device may include a first driving circuit which supplies the first group of data lines with driving signals for driving the dots, and a second driving circuit which supplies the second group of data lines with driving signals for driving the dots. Input data may be supplied to the first driving circuit and the second driving circuit through common lines.
The above structure is realized such that the driving circuit on one side is connected to different wiring plates on the one side, the wiring plates are connected to a further wiring plate, and display data lines are connected in parallel on the further wiring plate. This type of structure is preferable in that space for wiring can be reduced.
The display device may include a first driving circuit which supplies the first group of data lines with driving signals for driving the dots, and a second driving circuit which supplies the second group of data lines with driving signals for driving the dots. The first driving circuit may supply the first group of data lines with driving signals having polarities inverted between two adjacent data lines, and the second driving signal may supply the second group of data lines with driving signals which have polarities inverted between two adjacent data lines and which have inverse polarities compared with the driving signals supplied to the first group of data lines.
According to the above structure, the need for a scramble circuit is eliminated, and dot inversion is realized.
The display device may include a first driving circuit which supplies the first group of data lines with driving signals for driving the dots, and a second driving circuit which supplies the second group of data lines with driving signals for driving the dots. The first driving circuit may supply the first group of data lines with driving signals having polarities inverted between two adjacent data lines, and the second driving signal may supply the second group of data lines with driving signals which have polarities inverted between two adjacent data lines and which have identical polarities compared with the driving signals supplied to the first group of data lines.
According to the above structure, the need for a scramble circuit is eliminated, and dot inversion is realized.